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Finite Element Simulations on Failure Behaviors of Granular Materials with Microstructures Using a Micromechanics-Based Cosserat Elastoplastic Model

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computer Modeling in engineering & Sciences 2024年第3期138卷 2305-2338页

作者： Chenxi Xiu xihua Chu school of Civil engineering Chongqing Jiaotong UniversityChongqing400074China school of Civil engineering Wuhan UniversityWuhan430072China

This paper presents a micromechanics-based Cosserat continuum model for microstructured granular *** utilizing this model,the macroscopic constitutive parameters of granular materials with different microstructures are expressed as sums of microstructural *** microstructures under consideration can be classified into three categories:a medium-dense microstructure,a dense microstructure consisting of one-sized particles,and a dense microstructure consisting of two-sized ***,the Cosserat elastoplastic model,along with its finite element formulation,is derived using the extended Drucker-Prager yield *** investigate failure behaviors,numerical simulations of granular materials with different microstructures are conducted using the ABAQUS User Element(UEL)*** demonstrates the capacity of the proposed model to simulate the phenomena of strain-softening and strain *** study investigates the influence of microscopic parameters,including contact stiffness parameters and characteristic length,on the failure behaviors of granularmaterials ***,the study examines themesh independence of the presented model and establishes its relationship with the characteristic length.A comparison is made between finite element simulations and discrete element simulations for a medium-dense microstructure,revealing a good agreement in results during the elastic *** parameters describing plasticity are shown to be partially related to microscopic factors such as confining pressure and size of the representative volume element.

关键词： Granular materials micromechanics Cosserat elastoplastic model microstructures failure behaviors

M/S Controller Area Network(CAN) System Using Shared-Clock Scheduler

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武汉理工大学学报 2006年第S1期28卷 284-288页

作者： LIU Jianxin1,TAN Ping2.LIU Yu1 (1.school of Mechanical engineering & Automation,{2.,chengdu 610039,China 2.school of Mathematical & computer Science,{2.,chengdu 610039,China) school of Mechanical engineering & Automation Xihua UniversityChengdu 610039China school of Mathematical & computer Science Xihua UniversityChengDu 610039China

The Controller Area Network (CAN) is a well established control network for automotive and automation control applications. Time-Triggered Controller Area Network (TTCAN) is a recent development which introduces a session layer,for message scheduling,to the existing CAN standard,which is a two layer standard comprising of a physical layer and a data link layer. TTCAN facilitates network communication in a time-triggered fashion,by introducing a Time Division Multiple Access style communication scheme. This allows deterministic network behavior,where maximum message latency times can be quantified and guaranteed. In order to solve the problem of determinate time latency and synchronization among several districted units in one auto panel CAN systems,this paper proposed a prototype design implementation for a shared-clock scheduler based on PIC18F458 MCU. This leads to improved CAN system performance and avoid the latency jitters and guarantee a deterministic communication pattern on the bus. The real runtime performance is satisfied.

关键词： time-triggered controller area network auto panel shared-clock scheduler embedded System

Progress of Lyman-alpha-based beam emission spectroscopy(Ly BES)diagnostic on the HL-2. tokamak

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Plasma Science and Technology 2024年第3期26卷 118-125页

作者：周艺轩余羿许敏柯锐聂林徐皓赵光义刘灏袁子豪肖晨雨李继全肖池阶 the HL-2. Team Southwestern Institute of Physics Chengdu 610041People's Republic of China Sino-French Institute of Nuclear engineering and Technology Sun Yat-sen UniversityZhuhai 519082People's Republic of China State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871People's Republic of China

An edge Lyman-alpha-based beam emission spectroscopy(LyBES)diagnostic,using a heating NBI(neutral beam injection)system,is currently under development on the HL-2. *** 2.-channel edge LyBES,which is intended to measure the density fluctuation in plasma edge(from R=1960 mm to R=2.2. mm)with an improved spatial resolution of 3.3 mm,is a complement to the existing conventional beam emission spectroscopy(BES)*** this article,we introduce the progress of LyBES diagnostic,including the collection optics,the monochromator,and the detector *** reflectance of the collection mirrors is measured to be~82.at 12. nm,and the aberration geometrical radius of the collection optics is tested to be~150μm in the aimed *** linear dispersion of the LyBES monochromator is designed to be~0.09 nm mm^(-1).The bandwidth of the detector system with the 5×10^(7)V A^(-1)preamplifier gain is measured to be~2.0 kHz,and the peak-to-peak noise of the detector system is tested to be~16 *** finalized design,components development and testing of the LyBES diagnostic have been completed at present,and an overall performance of the LyBES diagnostic is to be confirmed in the next HL-2. campaign.

关键词： density fluctuation Ly BES BES vacuum ultraviolet

New Mg_2.i based Alloy for Automobile Engine Cylinder Liner

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Journal of Wuhan university of Technology(Materials Science) 2011年第4期26卷 797-800页

作者：张道文 school of Transportation and Automotive engineering Xihua University

New Mg2.i based alloy were prepared by mechanical alloying. Sintering temperature was from 82. to 865K, which indicated that few Mg2.i were produced at lower temperature while MgO were produced at higher temperature. Microstructure image showed that at sintering temperature of 855K, Mg2.i were mostly synthesized with the reaction of purity magnesia powder and silicon powder. Hardness and wear tests proved that the new synthetic silicon magnesium alloy had higher hardness and good wear resistance. Under the same testing conditions, it is found that the hardness of the new material is 42..50, and pure magnesium is only *** the same experiments it is also found that under the same pressure, pure magnesium alloys than silicon wearing capacity of pure magnesium is 2.times as high that of Mg2.i based alloy. It shows that Mg2.i based alloy is the ideal material for the wear parts of car engine cylinder liner because of its small density, stable dimension, high hardness and wear-resisting.

关键词： cylinder liner Mg2.i based alloy hardness wear-resisting

Theoretical analysis and experiment of micromechanics and mechanics-optics coupling of distributed optic-fiber crack sensing

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中国科学：技术科学英文版 2011年第S1期54卷 185-191页

作者： LIU HaoWu 1,2.CHEN Jiang 2.SUN Man 3 & DING Rui 2.1 State Key Laboratory of Hydraulics and Mountain River engineering,Sichuan university,{2. 610065,China 2.school of Water Resource Hydropower,Sichuan university,{2. 610065,China 3 school Electrical engineering and Information,Sichuan university,{2. 610065,China Sichuan Univ State Key Lab Hydraul & Mt River Engn Chengdu 610065 Peoples R China Sichuan Univ Sch Water Resource Hydropower Chengdu 610065 Peoples R China Sichuan Univ Sch Elect Engn & Informat Chengdu 610065 Peoples R China

The micromechanical behaviors and mechanics-optics coupling effects of optic-fiber-concrete complex in the distributed optic-fiber sensing concrete-crack technology,which was used in health monitoring of Wu Gorge Bridge on Yangtze River and a large dam successfully,have been investigated.A micromechanical theoretical analysis method and micromechanical frictional contact bi-interface model,as well as a modified optical theoretical analysis method of the mechanics-optics coupling effects are presented.A series of verification experiments,including mechanical experiments and mechanics-optics coupling experiments,have been *** results of micromechanical theoretical analysis and the analysis of the modified theory of mechanics-optics coupling along with mechanical and optical experimental data are shown to be in close *** the micromechanical theory and the modified theory of mechanics-optics coupling with their analysis methods can not only enhance credibility of this novel distributed sensing technology but also provide a way to understand its sensing mechanism and optimize its technical details and system.

关键词： optic-fiber sensing mechanics-optics coupling micromechanics health monitoring concrete structure crack detection

Uniform estimate for maximum of randomly weighted sums with applications to insurance risk theory

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Science China mathematics 2005年第10期48卷 1379-1394页

作者： WANG Dingcheng~1 SU Chun~2.& ZENG Yong~1 1. school of Management and school of Applied {2.,university of Electronic Science and Technology of China,chengdu 610054,China 2. Department of Statistics and Finance,university of Science and Technology of China,Hefei 2.002.,China 1. school of Management and school of Applied {2. University of Electronic Science and Technology of China 610054 Chengdu China 2. Department of Statistics and Finance University of Science and Technology of China 230026 Hefei China

This paper obtains the uniform estimate for maximum of sums of independent and heavy-tailed random variables with nonnegative random weights, which can be arbitrarily dependent of each other. Then the applications to ... 详细信息

关键词： dependent stochastic return, discount factor, heavy-tails, discrete time insurance risk model, maxima of randomly weighted sums, ruin probability, tail probabilities, uniformly asymptotic estimate.

Weighted composition operators between μ-Bloch spaces on the unit ball

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Science China mathematics 2005年第10期48卷 1349-1368页

作者： ZHANG Xuejun~1 & XIAO Jianbin~2.1. College of mathematics and computer Science,Hunan Normal {2.,Changsha 410006,China(email:xuejunttt@2.3. net) 2. The school of Science,Hangzhou Dianzi {2.,Hangzhou 310037,China 1. College of mathematics and computer Science Hunan Normal University 410006 Changsha China 2. The school of Science Hangzhou Dianzi University 310037 Hangzhou China

In this paper,necessary and sufficient conditions are given for the weighted composition operator T_(ψ,ψ) to be bounded or compact from the space β_μ to β_ν (or β_(μ,0) to β_(ν,0) ) on the unit ball of C^***... 详细信息

关键词： μ-Bloch space, weighted composition operator, boundedness, compactness.

An interpolating boundary element-free method (IBEFM) for elasticity problems

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Science China(Physics,Mechanics & Astronomy) 2010年第4期53卷 758-766页

作者： REN HongPing 1 , CHENG YuMin 2.& ZHANG Wu 1 1 school of computer {2. and Science, Shanghai university, Shanghai 2.0072. China 2.Shanghai Institute of Applied mathematics and Mechanics, Shanghai university, Shanghai 2.0072. China 1. school of computer {2. and Science Shanghai University Shanghai 200072 China2. Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

The paper begins by discussing the interpolating moving least-squares (IMLS) method. Then the formulae of the IMLS method obtained by Lancaster are revised. On the basis of the boundary element-free method (BEFM), combining the boundary integral equation method with the IMLS method improved in this paper, the interpolating boundary element-free method (IBEFM) for two-dimensional elasticity problems is presented, and the corresponding formulae of the IBEFM for two-dimensional elasticity problems are obtained. In the IMLS method in this paper, the shape function satisfies the property of Kronecker δ function, and then in the IBEFM the boundary conditions can be applied directly and easily. The IBEFM is a direct meshless boundary integral equation method in which the basic unknown quantity is the real solution to the nodal variables. Thus it gives a greater computational precision. Numerical examples are presented to demonstrate the method.

关键词： moving least-squares (MLS) approximation interpolating moving least-squares (IMLS) method boundary integral equation meshless method boundary element-free method (BEFM) interpolating boundary element-free method (IBEFM) elasticity problem

Manifold contraction for semi-supervised classification

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Science China(Information Sciences) 2010年第6期53卷 1170-1187页

作者： HU EnLiang 1,2., CHEN SongCan 1 & YIN XueSong 1 1 school of computer Science & {2., Nanjing university of Aeronautics & Astronautics, Nanjing 2.0016, China 2.school of mathematics, Yunnan Normal university, Kunming 650092. China 1. school of computer Science & {2. Nanjing University of Aeronautics & Astronautics Nanjing 210016 China2. School of Mathematics Yunnan Normal University Kunming 650092 China

The generalization ability of classification is often closely related to both the intra-class compactness and the inter-class *** to the fact that many current dimensionality reduction methods, regarded as a pre-processor, often lead to the poor classification performance on real-life data, in this paper, a new data preprocessing technique called manifold contraction(MC) is proposed for the classification-oriented learning *** main motivation behind MC lies in seeking a proper mapping of contracting the given multiple-manifold data such that the ratio of the intra-class to the inter-class scatters is ***, in order to properly control the contraction level in MC, an adaptive MC(AMC) criterion is developed in the semi-supervised *** to its generality, MC can be not only applied in original space and reproducing kernel Hilbert space(RKHS), but also easily incorporated with dimensionality reduction method for further improvement of classification *** final experimental results show that MC, as a data preprocessor, is effective and promising in the subsequent classification learning, especially in small-size labeled sample case.

关键词： manifold learning dimensionality reduction lower-dimensional embedding semi-supervised learning classification manifold contraction adaptive manifold contraction